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arXiv · 2108.09679

Metastable antiphase boundary ordering in CaFe$_{2}$O$_{4}$

H. Lane·E. E. Rodriguez·H. C. Walker·Ch. Niedermayer·U. Stuhr·R. I. Bewley·D. J. Voneshen·M. A. Green·J. A. Rodriguez-Rivera·P. Fouquet·S. -W. Cheong·J. P. Attfield·R. A. Ewings·C. Stock
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Abstract

CaFe$_{2}$O$_{4}$ is an $S=5/2$ antiferromagnet exhibiting two magnetic orders which shows regions of coexistence at some temperatures. Using a Green's function formalism, we model neutron scattering data of the spin wave excitations in this material, ellucidating the microscopic spin Hamiltonian. In doing so, we suggest that the low temperature A phase order $(\uparrow\uparrow\downarrow\downarrow)$ finds its origins in the freezing of antiphase boundaries created by thermal fluctuations in a parent B phase order $(\uparrow\downarrow\uparrow\downarrow)$. The low temperature magnetic order observed in CaFe$_{2}$O$_{4}$ is thus the result of a competition between the exchange coupling along $c$, which favors the B phase, and the single-ion anisotropy which stabilizes thermally-generated antiphase boundaries, leading to static metastable A phase order at low temperatures.

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H. Lane, E. E. Rodriguez, H. C. Walker, Ch. Niedermayer, U. Stuhr, R. I. Bewley, D. J. Voneshen, M. A. Green, J. A. Rodriguez-Rivera, P. Fouquet, S. -W. Cheong, J. P. Attfield, R. A. Ewings, C. Stock. 2021-08-22. Metastable antiphase boundary ordering in CaFe$_{2}$O$_{4}$. https://doi.org/10.1103/physrevb.104.104404

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